This invention relates to a rotary bleed valve assembly particularly but not exclusively for use with a gas turbine engine.
The concept of bleeding or recirculating a controlled variable proportion of compressor gases in a gas turbine engine is well-known. Usually a bleed valve assembly is utilised in the compressor gas flow which can allow bleeding of compressor gases to any desired degree. Hitherto, bleed valve assemblies for this purpose have utilised a valve member which moves rectilinearly across the gas glow to any necessary extent.
Problems arise with use of valve mechanisms which move rectilinearly in this way insofar as they can become easily seized or jammed due to the presence of pollutants in the compressor gases.
Also conventional bleed valves are typically pneumatically actuated and have response times of 200-500 ms. During this response time period, an excessive torsional load can be applied to the drive shafts of a gas turbine. The drive shafts therefore must be stressed accordingly, which increases the mass of the shafts and thereby the mass of the engine.